In hydraulic-turbines especially of the type in which the major components are submerged in water, problems arise with the fasteners used to secure components together. Bolts and nuts which are used gradually fail over the years due to fatigue and finally break. Through investigation it was found that the reason bolts and nuts failed was because of the cyclic loading and not being properly prestressed. To counter this condition studs were substituted for bolts and separate nuts engaged on the studs. To obtain the necessary high strength, the studs are of a stainless steel alloy which can be prestressed. The nuts could not be of the same material for they would gall and friction-weld to the studs. Thus, the removal of the nut from the stud could only be accomplished by cutting the nut and this damages the stud requiring that the stud be drilled out. To eliminate this problem the nut was manufactured of a nonweldable material and, thus, when engaged to the stud, would not gall or friction-weld thereto. However, this created another problem of maintaining the nut in prestressed relationship on the prestressed stud.